Surface of an ashtray



FIG. 1 is a perspective view of an ashtray incorporating my new surface design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevation view thereof; and,

FIG. 4 is rear elevation view thereof, the right side and left side elevational views being identical.

The broken lines depict environment and are not part of the claimed design. The design cannot be seen from the bottom view. 

The ornamental design for the surface of an ashtray, as shown and described. 